Sterilizer



Oct. 7, 1952 R L. JEWELL ET AL 2,613,130

' STERILIZER Filed Jan. 21, 1949 4 Sheets-Sheet l INVENTOIU W a W guou-ou/ Oct. 7, 1952 R. L. JEWELI. ET AL STERILIZER -4 Sheets-Sheet 3 Filed Jan. 21, 1949 m m m m z W 9 f W MM Oct. 7, 1952 R. L. JEWELL ET AL I 2,613,130

STERILIZER Filed Jan. 21, 1949 4 Sheets-Sheet 4 IN VEN TORS Patented Oct. 7, i952 STERILIZER Raymond L. Jewell and George J. Dyckes, Erie,

Pa., assignors to American Sterilizer Company, Erie, Pa., a corporation of Pennsylvania Application Januaryzl, 1949, Serial No. 71,808

ing with a drying period useful in reducing the moisture content of sterilized fabric materials during measurement of the water supply for a subsequent sterilizing cycle during the drying period, an on-ofif control for the sterilizin cycle, and an improved construction arrangement. Further objects. and advantages appear in the specification and claims.

In the drawings, Fig. 1 is a perspective of an autoclave; Fig. 2 is a diagrammatic perspective illustrating the operation; Fig. 3 is a control diagram; Fig. 4 is a side elevation of the control valve; Fig. 5 isa sectionjthrough the valve in the sterilize or onf position; Fig.',6 is a section through the control valve in the "ofi position; Fig. 7 is a sectional elevation of the steam trap and water measuringchamber; and Fig. 8 is a section on line 8-8 of Fig.7.;

The autoclave has a cabinet housing a rectangular sterilizer chamber 2 having its front end projecting through,-the front wall of the cabinet. The chamber is loaded andunloaded.

through a door 4"pivotally carried on a hinged bar 5. During sterilizing the door is clamped in sealing engagement with the front end of the chamber by a wingnut 6 and hinged bolt 1. Directly above the door is a control handle 8 movable between off and sterilize (on) ose tions. As shown more clearly in Fig. 4, the handle has a stem 9 extending through the front wall of the cabinet and carrying a plate I which is connected to a rotatable valve disk ll (Fig. 4) through pins l2. .The valve disk is held against a valve body 13 by a suitable, spring (not shown) and has ways l4 and I cooperating with ports IS, I1, 18, and IS in the valve body.

6 Claims. (01. zi -sm In the ofi" position of the control handle (Figs. 2, 6) the way l4 connects ports l6 and I1 so water can flow from a reservoir 20 in the upper part of the cabinet through a suitably perforated condenser coil 2!, a passageway 22 in the valve body, port It, way l4, and port I! to a conduit 23 leading to the lower end of a steam trap 24fixed-to the front end of a cylindrical water measuring chamber 25.- The meas- 2 fills the chamber by gravity. Air is ventedfrom the chamber 25 through a passage 26 to, the inside of a steam trap cover 21 surrounding a liquid filled bellows 28 controlling a valve 29 connected to a tube3ll having its open end '31 above the maximum water level in the reservoir. The valve 29 is closed only at steam temperatures so the valve is always open when necessary to vent air from the measuring chamber25.

The complete filling of the measuring chamber 25 obviously depends upon an adequate supply of water in the reservoir 20. The reservoir is filled through a sliding cover 32 on the top' of the cabinet. Full and Refill marks 33 and 34 are provided so the operator can keep an adequate supply of water in the reservoir.

While the handle is in the off position, the

bottom of a well 35 in the bottom wall of the sterilizing chamber 2 is connected through a fitting 36, a conduit 37, port I8, way 15 and port [9 to an anti-syphon exhaust tube 38 looped above the water level in the reservoir 20 and discharging to the passage 22. This permits steam-and water within the sterilizing chamber to blow into the perforated condenser coil 21 where the steam and water are cooled and returned to the reservoir. Back syphonage of reservoir to the sterilizing chamber following the exhaust of the chamber pressure is prevented by a small vent hole 39 (Fig. 4).

Upon movement of the control handle 8 to the fon or sterilize position the valve disk H is turned to the position shown in Fig. 5 in which the way I 4 connects the valve ports 11 and I8 and the way I5 connects the valve ports It and [9. This breaks the connection between the:

reservoir 20 and the measuring chamber 25 and establishes a connection between the measurin chamber 25 and. the conduit 31 so that the contents of the measuring chamber 25 flow into the well 35 at the bottom of the sterilizing charm matically indicated (Fig. 3) as comprising a pivoted arm 42 carrying a contact 43 which 00- operates with a stationary contact 44. A spring a acts as an overcenter. device to hold the arm 42 in either the opened or in the closed position. Closing the switch 4| establishes an electrical circuit from a line contact 45 through contacts 43 and 44 of the switch 4|, conductor 46, thermostatically controlled contacts 41 and conductor 48 to one side of heating elements 49 mounted on the bottom wall of the well 35. The other side of the heating elements is connected through a conductor 50 to the other line contact A red signal light 52 is connected across the heating elements 49 so that whenever the heating elements are energized at full voltage the signal light 52 glows indicating that the sterilizing operation has started. The steam generated by the heat from the heating elements 49 drives off the air within the sterilizing chamber through a vent conduit 53 having its lower end connected to the sterilizing chamber well above the water level in the Well 35 and leading to the steam trap 24. The air blows through a passageway 55 in the steam trap and out through the valve 29 controlled by the bellows 28. As the air is driven off the temperature of the bellows 28 increases resulting in a closing of the valve 29 after which the temperature in the sterilizing chamber builds up to the full pressure which is determined by the setting of an adjusting knob 56 for the thermostatically controlled contacts 41. Because the heating elements 49 have a fixed power input and are heating a measured quantity of water it requires a definite time for the temperature of the sterilizer chamber to reach the desired maximum value necessary to sterilize the contents. Upon reaching the maximum temperature selected by the adjustment of the knob 56 the liquid in a bulb 51 located slightly above the bottom wall of the well 35 (so as to be sub-merged in the heated water) expands a bellows 58 having a mechanical connection indicated by dotted lines 59 with an arm 60 carrying one of the thermostatically controlled contacts 41. The expansion of the bellows 58 causes the contacts 41 to open when the temperature in the sterilizer chamber reaches the value selected by the adjustment of the knob 56. Upon opening of the contacts 41 a green signal light 6| is connected in series with the signal lamp 52 and the heating elements 49. This permits only a very slight flow of current which is insuflicient to illuminate the signal bulb 52 but is sufficient to illuminate the green signal bulb 6 I. This indicates to the operator that the sterilizing is complete. If the operator should neglect to notice the lighting of the green signal bulb 6| the thermostatic contacts 41 will reclose as soon as the temperature in the sterilizer chamber drops below the selected value and will again open after a succeeding heating cycle.

If for any reason the water supply in the well 35 becomes exhausted before the temperature in the sterilizer chamber reaches the selected value, the bulb 51 will lag behind the temperature rise of the well due to the fact that the bulb 51 will no longer be immersed in water and will receive heat at a slower rate. This will result in an overheating of the walls of the well 35 and of the sterilizer chamber 2 so that when the bulb 51 reaches a temperature sufficient to open the contacts 41 there will be enough stored heat to cause a further rise in the bulb temperature which will cause an additional expansion of the bellows 58. This additional expansion is communicated to the switch 4| through a mechanical connection indicated by dottedlines 62. The magnitude of this additional expansion of the bellows 58 is sufiicient to move t e arm 2 over center thereby opening the contacts 43 and 44. Due to the overcenter spring the contacts 43 and 44 will remain in the open position. This provides a safety shut-down of the sterilizer when there is insufilcient water for safe operation.

Upon lighting of the green light 6| signalling the end of the sterilizing cycle the operator moves the handle 8 to the off position. This connects the conduit 31 through the port i8, way I5, and port |9, to the exhaust tube 38 so that the steam and any residual water in the well is blown through the conduit 31 into the condenser 2|. At the same time the reservoir 20 is connected through the port l6, way l4, and port H to the conduit 23 leading to the measuring chamber 25, thereby filling the measuring chamber with the proper quantity of water for a succeeding sterilizing cycle immediately following the exhaust of pressure from the chamber.

As soon as the water has been blown out of the well 35 the thermostatic bulb 51 is no longer immersed in water and is in a position where the heat transfer to the bulb is lowered. Since heat is still being applied to the heating elements'49 the temperature of the walls of the well 35 and of the sterilizer chamber 2 increases at a faster rate than the temperature of the bulb 51 and from one aspect the chamber becomes a'drying oven. When the bulb 51 finally reaches a temperature sufficient to open the thermostatic contacts 41 there is enough stored heat so that the contacts 43 and 44 are opened as described above in connection with the safety shut-down in case of low water. This increase in the sterilizing wall chamber temperature at the end of the sterilizing cycle is desirable since it reduces the moisture in sterilized fabric ma terials. From one aspect the safety control for insufficient water supply is used to introduce an automatic drying cycle at the end of the steri1- izing cycle. I

In the use of the sterilizer, chamber 2 is loaded while the control 8 is in the off position. The door 4 is then clamped in sealing engagement with the end of the sterilizing chamber by tightening wing nut 6. The sterilizing cycle is started by moving the control handle 8 to the on or sterilizing position and pushing the button 40 to close the contacts 43 and 44 of the switch 4|. In the sterilize position of the control, the measured quantity of water in chamber 25 drains into the well 35 and it is converted to steam by heat from the heating elements 49. Red signal light 52 lights up indicating to the operator that the sterilizing cycle is in progress. The temperature within the sterilizing chamber is indicated by a thermometer 63 carried in the front end of the steam trap 24. The steam trap also has a safety .relief valve 65 which protects the sterilizing chamber against overpressure. As soon as the temperature in the sterilizing chamber reaches the value selected by the knob 56, the thermostatic contacts 41 are opened by expansion of the bellows 58 associated with the bulb 51 slightly above the bottom wall of the well 35. Opening of the contacts 41 connects the green signal light 6| in series with the red signal light 52. The red light goes out and the green light comes on indicating to the operator that the sterilizing cycle is completed. The operator, while the green light is on, moves the control handle 8 to the ofi position. This connects the bottom of the well 35 through the conduit 31 to the condenser 2| causing the steam and any water remaining in ae aieo the sterilizingchamber'to be blown into the reservoir 20. At the end of the blow off period the temperature within the chamber, drops sufficiently to causea re-closing of ithe thermostatic contacts 41 and a re-connection of the heating elements 49 to the powersupply. This causes the lighting of the redsignal light 52. .The red signal light remains lighted until the temperature of the walls of the well 35 and sterilizing chamber 2 have been raised sufficiently-to cause. opening of the contacts 43, 44 of the switch 4 l. Theop'ening of these contacts breaks the power connection and causes both signallights 52-v and 61;; toei'go out. This indicates to the operator that-the sterilizing cycle has been completed and it is safe to open the door 4 and remove the sterilized contents.

The sterilizer is adapted for operation from the standard electrical wall outlet which is limited to a power output of approximately 1600 watts. With this limited power it is important that the water supplied to the sterilizing chamber be no more than adequate for the sterilizing operation. Another advantage of the accurate measurement of the water supply is that it reduces the load on the condenser and prevents overheating of the water in the reservoir which is used for condensing purposes. The operation of the sterilizer is essentially independent of the size and type of load of material to be sterilized. Variations in the quantity or kind of material to be sterilized are automatically compensated for. To use the sterilizer the operator need only push the start button and move the control handle to the on and off positions. The sterilizer can be reused to process another load immediately after the preceding load is removed without waiting for the sterilizer to cool.

What we claim as new is:

1. In a sterilizer, a pressure sterilizing chamher for receiving material to be sterilized and a water supply for generation of steam, means for heating the water supply received in the chamber to a sterilizing temperature and pressure above atmospheric, a water reservoir, a water measuring chamber, a condenser coil discharging to the reservoir, a valve control connecting the measuring chamber to the reservoir and the lower part of the sterilizing chamber to the condenser whereby the measuring chamber is filled and the steam and water'in the sterilizing chamber is discharged to the condenser and alternatively connecting the measuring chamber to the sterilizing chamher and closing the connection to the condenser whereby the sterilizing chamber is supplied with the measured quantity of water.

2. In a sterilizer, a pressure sterilizing chamber for receiving material to be sterilized and a water supply for generation of steam, means for heating the water supply received in the chamber to a sterilizing temperature and pressure above atmospheric, a water reservoir, a water measuring chamber, a condenser coil discharging to the reservoir, a control valve having a sterilize position connecting the measuring chamber to the sterilizing chamber whereby the sterilizing chamber is supplied with the measured quantity of water, and an off position connecting the lower part of the sterilizing chamber to the condenser and the water reservoir to the measuring chamber whereby the measuring chamber is filled and the steam and water in the sterilizing chamber is discharged to the condenser.

3. In a sterilizer, a pressure sterilizing chamher for receiving material to be sterilized and a. water supply for-generation of steam, means ior lheating .the water "supply received in the chamber to a-sterilizing vtemperature and pressureabove atmospheric, .a- -water reservoir, a, water :mcasuring chamber, ,;a J condenser; coil discharging to the reservoir, -.acontrol valve-having -aj--sterilize position connecting the measuring chamber to r the sterilizing chamber whereby the sterilizing chamberis supplied with the measured quantity of water, and;an-off position connecting the lower part of the sterilizing chamber andmeasuring chamber't'o' the condenser whereby the-measuringchamber is filled and the steam and water in the sterilizing chamber is discharged to the condenser.

4-. In a sterilizer, a pressure sterilizing chamber for receiving material to be sterilized and a water supply for generation of steam, a water reservoir, a water measuring chamber, a condenser coil discharging to the reservoir, a control valve having a sterilize position connectin the measuring chamber to the sterilizing cham-- ber whereby the sterilizing chamber is supplied with the measured quantity of water and an off position connecting the lower part of the sterilizing chamber to the condenser and the water reservoir to the measuring chamber whereby the measuring chamber is filled and the steam and water in the sterilizing chamber is discharged to the condenser, means for heating the sterilizing chamber walls to generate steam at a sterilizing temperature and pressure above atmospheric and a thermostat responsive to superheating of the chamber walls above sterilizing temperature upon discharging of the steam and water from the sterilizing chamber to the condenser for cutting off the heating means.

5. In a sterilizer, a pressure chamber for material to be sterilized, a portion of the chamber being constructed to hold water for generating steam, an electric heating element for said portion of the chamber, a water reservoir, a condenser therein, a water measuring chamber, thermostatic contacts responsive to the steam temperatures in the chamber above atmospheric pressure for tie-energizing the heating element until the temperature drops, a signal device across the contacts energized upon opening of the contacts for indicating the de-energizing of the heating element, another signal device across the heating element energized upon closing of the contacts indicating energizing of the heating element, a control valve having a sterilize position connecting the measuring chamber to the sterilizing chamber whereby the sterilizing chamber is supplied with the measured quantity of water and an off position connecting the lower part of the sterilizing chamber to the condenser and the water reservoir and measuring chamber whereby the measuring chamber is filled and the steam and water in the sterilizing chamber is discharged to the condenser, and thermostatic contacts responsive to superheating of the chamber walls above sterilizing temperature for cutting off the heating element and signal devices.

6. In a sterilizer, a pressure chamber for holding material to be sterilized, said chamber holding a water supply in its lower part, a heater of higher temperature than any to be utilized in the chamber for heating the chamber Walls to generate steam at a sterilizing temperature and pressure above atmospheric, a thermostat within the chamber and spaced from the walls thereof but in contact with the water supply in the lower part of the chamber for controlling the heater 8 in response to the steam temperature during a. REFERENCES CITED sterilizing cyclea water dram from the lower The following references are of record in the part of the chamber, control means for dischargfil of this patent; ing the steam and water through said drain at the end of the sterilizing cycle while continuing 5 UNITE]? STATES PATENTS the operation of the heater so the chamber be- Number Name Date comes a drying oven, and means responsive to 516,416 Van Heusen Mar. 13, 1894 overheating of the thermostat caused by heating 573,213 Kellogg Dec. 15, 1896 of the chamber walls above steam temperature 698,711 Kellogg Apr. 29, 1902 for cutting off the heater. :0 1,810,545 mpiano June 16, 1931 1,850,923 Danzer Mar. 22, 1932 RAYMOND JEWELL- 1,930,551 Blashfleld Oct. 17, 1933 O G ES-- 1,939,714 Mietzler Dec. 19, 1933 

1. IN ASTERILIZER, A PRESSURE STERILIZING CHAMBER FOR RECEIVING MATERIAL TO BE STERILIZED AND A WATER SUPPLY FOR GENERATION OF STEAM, MEANS FOR HEATING THE WATER SUPPLY RECEIVED IN THE CHAMBER TO A STERILIZING TEMPERATURE AND PRESSURE ABOVE ATMOSPHERIC, A WATER RESEVROIR, A WATER MEASURING CHAMBER, A CONDENSER COIL DISCHARGING TO BE RESERVOIR, A VALUE CONTROL CONNECTING THE MEASURING CHAMBER TO THE RESERVOIR AND THE LOWER PART OF THE STERILIZING CHAMBER TO THE CONDENSER WHEREBY THE MEASURING CHAMBER IS FILLED AND THE STEAM AND WATER IN THE STERILIZING CHAMBER IS DISCHARGED TO THE CONDENSER AND ALTERNATIVELY CONNECTING THE MEASURING CHAMBER TO THE STERILIZING CHAMBER AND CLOSING THE CONNECTION TO THE CONDENSER WHEREBY THE STERILIZING CHAMBER IS SUPPLIED WITH THE MEASURED QUANTITY OF WATER. 